Steam-engine



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W. A. PITT.

. STEAM ENGINE; No. 546,055.` Patented Sept. 10,1895.

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W. A. PITT.

STEAM ENGINE. No. 546,055. Patented Sept. 10, 1895- v\ /1T1\1ESSES; f. [MEMO-...

' WMe-4 a CPA/5 A B Nirn STATES WILLIAM A. PITT, OF MANHASSET, NFV YORK.

STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent No. 546,055, dated September 10, 1895.

Application filed March 8, 1895.

To all whom t may concern.-

Beit known that I, WILLIAM A. PITT, a citizen of the United States, residing at Manhasset,in the county of Queens and State ofNew York, have invented certain new and useful Improvements in Steam-Engines, of which the following is a specification.

My invention relates to the class of engines wherein a series of cylinders are grouped about a shaft to be driven, the piston-rods from the pistons in the cylinders being made, by some intermediate mechanism, to convert the alternate reciprocating motion of the pistons into continuous rotary motion of the shaft.

The invention will be fully described hereinafter, with reference to the accompanying drawings, and its novel features carefully defined in the claims.

In the said drawings, Figure 1 is a vertical section of an engine embodying myinvention, the plane of the section being indicated by the line a2 0c in Fig. 2. Fig. 2 is a horizontal section of the engine in the plane indicated by the line :r2 c2 in Fig. l. Fig. 3 is a view on a larger scale than Figs. 1 and 2, showing the valve mechanism in elevation. Fig. 4 is a side elevation of the engine, showing mode of mounting it to rock in bearings. Fig. 5Vis a view illustrating a modified construction of the valves and their operating mechanism.

In general the engine comprises a central body, in which the main shaft is rotatively mounted, and four-cylinders connected or integral with the central body and arranged in pairs, the axes of the pairs of cylinders crossing each other at right angles at the axis of the main shaft.

l represents the body of the engine, 2 and 2X one pair of cylinders, and 3 and 3X the other pair of cylinders. Within the body or central frame of the engine is a chamber 4, into which open the inner ends of the several single-actin g cylinders. This chamber is closed at the front by a removable cover 1X. (Seen in Fig. 2.)

In the cylinders 2 and 2X are'pistons 5 and 5*,the rods of which are connected rigidly to a rectangular cam-yoke 6, and likewise in the cylinders 3 and 3X are pistons 7 and 7X, the rods of which are connected rigidly to a rectangular cam-yoke 8. Fixed on the main serai no. 540,952. i da model.)

shaft 9 are two like equilateral triangular cams 10 and 11, which are set oppositely on the shaft and are situated within the respective yokes 6 and 8. Alternate reciprocating movement of the pairs of coupled pistons causes the cam-yokes 6 and S to act on their respective cams 10 and 11 and impart continuous rotary motion to the main shaft 9, which has bearings in the rear wall of the body l and its cover 1X, as shown in Fig. 2.

Mounted on one side orl face ofthe body 1 is a valve-casing or steam-chest 12, in which are situated four valves-one for each cylinder-and avalve-operating mechanism. y The steam entersthe steam-chest from a pipe 13, passes to the respective cylinders by ports and passages 14, (see Fig. 2,) and exhausts-by ports 15 into a common annular port-passage, (seen in dotted lines in Fig. 3,) which has an exhaust-outlet 16.

Figs. 2 and 3, the latter especially, illustrate the construction and operation of the valves and their operative mechanism. The valves 2a, 2X2", 3, and 3X control the induction and eduction ports of the respective cylinders 2, 2X, 6, and 3X. These are ordinary slide-valves and are all alike. They playin guides 17 and are coupled by links 1S to the respective sides of a square cam-yoke 19, inclosed Within a square guide-frame 20, room being provided within the frame for the movement of the yoke. On the extremity of the main shaft which extends into the steam-chest is fixed an equilateral triangular cam 2l,which fits snugly within the square yoke 19, and rotationof the cam imparts a four-motion movement to the yoke, which motion is transmitted tothe respective valves by the coupling-links 18. The yoke 19 moves about within the guide-frame 2O with one of its sides always in contact with the adj acent'side of the guideframe, only a film of steam being interposed between them. The operation of the valves will be readily understood. While one pair of oppositely-arranged valves are being shifted the other pair remain inactive, the movement of the yoke 19 transversely of their path producing only a very slight movement of them through the lateral swing of the. coup-V4 ling-links 18.

The cams 10, l1, and 21, which are all alike uexcept as to throw, are laid out as follows:

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An equilateral triangle is laid out a side of which is equal to the throw or movement imparted to the yoke by aquarter-rotation of the cam. The curved contour of the cam is drawn from centers at the apices of this triangle.

Fig. illustrates a construction wherein the several valves are integral with the yoke 19 or fixed rigidly thereto. About the yoke or forming a part thereof is a web 19X, the edge of which moves along the sides of the guideframe 2O when the engine is in motion. Instead of being situated as in Fig. 3 the induction and eduction ports are in this construction arranged abreast and a notch or recess 14X is formed in the margin of the web K 19X, which in the operative movement of the valve is brought to coincide with the induction-port 14 and thus permit the live steam to enter thereat. The induction-port will be alternately opened to the live steam and the exhaust, as in any slide-valve engine; but there will be a period at the end of the stroke of each piston when the steam will be held in that cylinder by the closure of both theinduction and eduction ports thereof. Each piston acts in succession on the cams 10 and 11-for example, first 5, then 7, then 5X, and

then 7X. This form of valve shown in Fig. 5 will operate precisely the same as that shown in Fig. 3; but I prefer the latter for reasons not necessary to explain.

I will now explain the manner of mounting the engine, as best illustrated in Figs. 1 and 4, and the reasons therefor.

On a suitable bed-plate 22 are two uprights or pillow-blocks 23, fitted at their upper ends to receive and form bearings for the two horizontally-arran ged cylinders, which are mounted in the pillow-blocks in the manner of trunnions, being retained by caps 24. This construction enables the main shaft to be set at any desired angle with the horizon. When set as desired, the engine `is secured in its bearings by means of a set-screw 25. Such a mounting adapts the engine for the operation of drills in mines and for like purposes; but I do not limit myself to any particular kind of bed-plate or mounting for the engine.

I have shown the four cylinders arranged with their axes in the same plane, and thisis the most convenient arrangement; but it is obviously not essential to my invention.

I am aware, of course, that four-cylinder or cross engines are not new; but in all of these, so far as I am aware, the main shaft is cranked and pins of the crank engage slotsin the connecting-rods of the pairs of pistons. This construction has, ofcourse, all the disabilities attendant upon the ordinary engine-crank. By my use of the equilateral triangular cams to receive the impulses from the pistons successively I not only avoid a crank inthe engineshaft, which stiffens the construction, but I attain, in effect, a constant crank-leverage for the entire rotation of the shaft which is equal to the maximum crank-leverage in an engine where an ordinary crank is used and in which the average crank-leverage is only one-half the maximum. In my engine only one piston acts at atime, and each acts through aquadrant of the full revolution.

Having thus described my invention, I claim-- 1. An engine having four cylinders arranged about the shaft in pairs with the axes of the respective pairs at right-angles to each other, the piston-rods of each pair of cylinders being connected rigidly to a cam-yoke which embraces an equilateral, triangular cam on the main shaft, whereby substantially the full effective pressure is obtained throughout the stroke of the piston and valves, operated by the main shaft, and controlling theinduction and eduction-ports of the cylinders, substantially as set forth.

2. In an engine, the combination, with the engine-body, the two pairs of cylinders, their pistons and piston-rods, the main shaft, mounted in the engine-body, the equilateral, triangular cams 10 and 11, set oppositely on said shaft, and the yokes embracing said cams and rigidly fixed tothe respective piston-rods, as described, of the steam-chest, furnlshed with induction and eduction-ports for the respective cylinders, the equilateral, triangular cam 21, the square yoke 19, embracing said cam, the fixed guideeframe 20, in the steamchest and about the yoke 19, and the valves, connected with said yoke and adapted to control the several induction and eduction ports, substantially as set forth.

3. In a four-cylinder engine, the combination with the engine-body, the said cylinders, their pistons and piston-rods, the main shaft, and mechanism intermediate the piston-rods and said shaft whereby the former impart rotary motion to the latter, of the steam-'chest provided with induction and eduction ports for the several cylinders, the equilateral, triangular cam, 21,'on the shaft within the steamchest, the square yoke embracing said cam, its guide, fixed in the steam-chest, the valves controlling the induction and eduction-ports, their guides, andthe links connecting the several valves with the said square yoke, substantially as set forth.

4. The combination with a bed-plate having pillow-blocks thereon, as described, of an engine having a body, four cylinders arranged about said body in pairs, the cylinders of one pair being mounted as trunnions in said pillow-blocks, and a main shaft having bearings in said engine-body, substantially as set forth.

In witness whereofI have hereunto signed my name in the presence of two subscribing witnesses.

WILLIAM A. PITT.

Witnesses:

HENRY CONNETT, PETER A. Ross.

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